Laziness can come with a performance cost, but the Haskell folks have
done lots of good work on strictness analysis. In exchange, you can
write conditional constructs without needing macros, streams, infinite
data structures, some performance <em>gains</em>, and easier semantics
for recursive expressions.

Uniqueness typing has <a href="http://home.pipeline.com/~hbaker1/Use1Var.html">many many
advantages</a>, so we'll
use that instead of nasty monads. But we can do monads too, when
they're useful.

Haskell-style typeclasses and generic functions are used to provide
polymorphism, rather than class- or prototype-based object
orientation.

us an "Any" type we can use in those cases.

Dependant types are awesome, too. Let's have those while we're at
it. We're now wel into "Type system is Turing complete" territory, so
we'd better have function totality as part of the type system to keep
our type expressions halting.

<a href="https://www.idris-lang.org/">Idris</a> does a pretty epic job of making
such a type system work in practice, but I do find the Haskelly syntax
for types a bit obtuse at times; it's too pattern-matchy for me. The
way constraints are written in "design by contract" languages (eg,
Eiffel) are much more readable, to my eyes at least - and as far as I
can see, identical in expressiveness. Design by Contract and dependent
types are much the same idea, just expressed in different ways, so
let's bring them together; we can statically check the constraints